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The single Drosophila ZO-1 protein Polychaetoid regulates embryonic morphogenesis in coordination with Canoe/afadin and Enabled.

Choi W, Jung KC, Nelson KS, Bhat MA, Beitel GJ, Peifer M, Fanning AS - Mol. Biol. Cell (2011)

Bottom Line: Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure.The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together.Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of North Carolina at Chapel Hill, USA.

ABSTRACT
Adherens and tight junctions play key roles in assembling epithelia and maintaining barriers. In cell culture zonula occludens (ZO)-family proteins are important for assembly/maturation of both tight and adherens junctions (AJs). Genetic studies suggest that ZO proteins are important during normal development, but interpretation of mouse and fly studies is limited by genetic redundancy and/or a lack of alleles. We generated alleles of the single Drosophila ZO protein Polychaetoid (Pyd). Most embryos lacking Pyd die with striking defects in morphogenesis of embryonic epithelia including the epidermis, segmental grooves, and tracheal system. Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure. However, Pyd loss does affect several cell behaviors that drive dorsal closure. The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together. Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

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pydMZ mutants can assemble and maintain adherens junctions and assemble a leading edge actomyosin cable. Stage 13 or 14 wild-type (WT) or pydMZ mutants, anterior left, dorsal view, antigens indicated. (A, B) Early stage 14. Arrow indicates leading edge actin cable. (C, D) Stage 14. Arrow indicates leading edge myosin cable. Inset, magnified view of leading edge cable. Blue arrowheads, LE cells with constricted leading edges and elevated myosin staining. Magenta arrowheads, LE cells with broadened leading edges and reduced myosin staining. (E–G) Early (E, F) or late (G) stage 14. Arrow indicates leading edge myosin cable. Scale bars, A–G, 10 μm; H–K, 1 μm.
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Figure 3: pydMZ mutants can assemble and maintain adherens junctions and assemble a leading edge actomyosin cable. Stage 13 or 14 wild-type (WT) or pydMZ mutants, anterior left, dorsal view, antigens indicated. (A, B) Early stage 14. Arrow indicates leading edge actin cable. (C, D) Stage 14. Arrow indicates leading edge myosin cable. Inset, magnified view of leading edge cable. Blue arrowheads, LE cells with constricted leading edges and elevated myosin staining. Magenta arrowheads, LE cells with broadened leading edges and reduced myosin staining. (E–G) Early (E, F) or late (G) stage 14. Arrow indicates leading edge myosin cable. Scale bars, A–G, 10 μm; H–K, 1 μm.

Mentions: In addition to their role in TJs, mammalian ZO family proteins play roles in the proper maturation of AJs in cultured cells. To test the hypothesis that Pyd plays a similar role, we examined localization of AJ proteins in pydMZ mutants. We found no defects in localization of the epithelial classic cadherin DE-cadherin (Figure 3, A’ vs. B’) or in localization of Armadillo (Arm; fly β-catenin; Figure 3, C’ vs. D’). Even in relatively late mutant embryos, both proteins localized correctly, as did cortical actin, which underlies AJs (Figure 3, A’’’ vs. B’’’, and unpublished data). We also examined cross sections and found no change in the enrichment of Arm in apical AJs in pyd mutants in either the epidermis (Figure 3, H vs. I) or the amnioserosa (Figure 3, J vs. K). Finally, we examined accumulation and localization of Cno (fly afadin), a known AJ protein and Pyd binding partner. Cno levels and localization were also apparently unaffected by Pyd loss (Figure 3, A’’ vs. B’’). Thus in Drosophila the sole ZO family member is not required for assembly or maintenance of AJs.


The single Drosophila ZO-1 protein Polychaetoid regulates embryonic morphogenesis in coordination with Canoe/afadin and Enabled.

Choi W, Jung KC, Nelson KS, Bhat MA, Beitel GJ, Peifer M, Fanning AS - Mol. Biol. Cell (2011)

pydMZ mutants can assemble and maintain adherens junctions and assemble a leading edge actomyosin cable. Stage 13 or 14 wild-type (WT) or pydMZ mutants, anterior left, dorsal view, antigens indicated. (A, B) Early stage 14. Arrow indicates leading edge actin cable. (C, D) Stage 14. Arrow indicates leading edge myosin cable. Inset, magnified view of leading edge cable. Blue arrowheads, LE cells with constricted leading edges and elevated myosin staining. Magenta arrowheads, LE cells with broadened leading edges and reduced myosin staining. (E–G) Early (E, F) or late (G) stage 14. Arrow indicates leading edge myosin cable. Scale bars, A–G, 10 μm; H–K, 1 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 3: pydMZ mutants can assemble and maintain adherens junctions and assemble a leading edge actomyosin cable. Stage 13 or 14 wild-type (WT) or pydMZ mutants, anterior left, dorsal view, antigens indicated. (A, B) Early stage 14. Arrow indicates leading edge actin cable. (C, D) Stage 14. Arrow indicates leading edge myosin cable. Inset, magnified view of leading edge cable. Blue arrowheads, LE cells with constricted leading edges and elevated myosin staining. Magenta arrowheads, LE cells with broadened leading edges and reduced myosin staining. (E–G) Early (E, F) or late (G) stage 14. Arrow indicates leading edge myosin cable. Scale bars, A–G, 10 μm; H–K, 1 μm.
Mentions: In addition to their role in TJs, mammalian ZO family proteins play roles in the proper maturation of AJs in cultured cells. To test the hypothesis that Pyd plays a similar role, we examined localization of AJ proteins in pydMZ mutants. We found no defects in localization of the epithelial classic cadherin DE-cadherin (Figure 3, A’ vs. B’) or in localization of Armadillo (Arm; fly β-catenin; Figure 3, C’ vs. D’). Even in relatively late mutant embryos, both proteins localized correctly, as did cortical actin, which underlies AJs (Figure 3, A’’’ vs. B’’’, and unpublished data). We also examined cross sections and found no change in the enrichment of Arm in apical AJs in pyd mutants in either the epidermis (Figure 3, H vs. I) or the amnioserosa (Figure 3, J vs. K). Finally, we examined accumulation and localization of Cno (fly afadin), a known AJ protein and Pyd binding partner. Cno levels and localization were also apparently unaffected by Pyd loss (Figure 3, A’’ vs. B’’). Thus in Drosophila the sole ZO family member is not required for assembly or maintenance of AJs.

Bottom Line: Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure.The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together.Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of North Carolina at Chapel Hill, USA.

ABSTRACT
Adherens and tight junctions play key roles in assembling epithelia and maintaining barriers. In cell culture zonula occludens (ZO)-family proteins are important for assembly/maturation of both tight and adherens junctions (AJs). Genetic studies suggest that ZO proteins are important during normal development, but interpretation of mouse and fly studies is limited by genetic redundancy and/or a lack of alleles. We generated alleles of the single Drosophila ZO protein Polychaetoid (Pyd). Most embryos lacking Pyd die with striking defects in morphogenesis of embryonic epithelia including the epidermis, segmental grooves, and tracheal system. Pyd loss does not dramatically affect AJ protein localization or initial localization of actin and myosin during dorsal closure. However, Pyd loss does affect several cell behaviors that drive dorsal closure. The defects, which include segmental grooves that fail to retract, a disrupted leading edge actin cable, and reduced zippering as leading edges meet, closely resemble defects in canoe zygotic mutants and in embryos lacking the actin regulator Enabled (Ena), suggesting that these proteins act together. Canoe (Cno) and Pyd are required for proper Ena localization during dorsal closure, and strong genetic interactions suggest that Cno, Pyd, and Ena act together in regulating or anchoring the actin cytoskeleton during dorsal closure.

Show MeSH